class Car():
  def __init__(self, make, model, year):
    self.make = make
    self.model = model
    self.year = year
    self.odometer_reading = 0
  def get_descriptive_name(self):
    long_name = str(self.year) + ' ' + self.make + ' ' + self.model
    return long_name.title()
  def read_odometer(self):
    print("This car has " + str(self.odometer_reading) + " miles on it.")
  def update_odometer(self, mileage):
    if mileage >= self.odometer_reading:
       self.odometer_reading = mileage
    else:
       print("You can't roll back an odometer!")
  def increment_odometer(self, miles):
    self.odometer_reading += miles

class Battery():
# """ 一次模拟电动汽车电瓶的简单尝试 """
  def __init__(self, battery_size=70):
# """ 初始化电瓶的属性 """
         self.battery_size = battery_size
  def describe_battery(self):
# """ 打印一条描述电瓶容量的消息 """
         print("This car has a " + str(self.battery_size) + "-kWh battery.")
  def upgrade_battery(self):
      if self.battery_size != 85:
          self.battery_size = 85
  def get_range(self):
# """ 打印一条消息，指出电瓶的续航里程 """
     if self.battery_size == 70:
        range = 240
     elif self.battery_size == 85:
        range = 270
     message = "This car can go approximately " + str(range)
     message += " miles on a full charge."
     print(message)
     self.upgrade_battery()

class ElectricCar(Car):
    def __init__(self, make, model, year):
       super().__init__(make, model, year)
       self.battery = Battery()

my_tesla = ElectricCar('tesla', 'model s', 2016)
my_tesla.battery.get_range()
my_tesla.battery.upgrade_battery()
my_tesla.battery.get_range()